Evaporator for refrigerators



Feb. 7, 1933. c, w MASON 1,896,412

EVAPORATOR FOR REFRIGERATORS FilegA'pr il 11. 1929 INVENTOR ATTORNEY Patented Feb. 7, 1933 GEORGE W. MASON, F DETROIT, MICHIGAN,

ASSIGNOR TO KELVINATOR CORPORATION,

01' DETROIT, MICHIGAN, ACORPORATION OEMICHIGAN EVAPOBATOR FOR REFRIGERATOBQ Application filed April 11,

This invention relates to artificial refrig eration apparatus; and it has particular relation to apparatus of the above named character, which shall be specially applicable in 5 refrigeration cabinets for domestic use.

An object of the invention is to provide an apparatus in which water, or food products of any character whatever, can be inserted in the apparatus in ainetallic or other suitable tray, and frozen in a relatively short time.

Another object of the invention is to provide an apparatus in which the operation of a condensing unit of a refrigeration appa-' ratus will be controlled automatically in response to the temperature of substances contained in a freezing tray adapted to be inserted in an evaporating unit employed in such apparatus.

Another object of the invention is to provide a refrigeration apparatus in which the operation of the condensing unit thereof, will be initiated automatically upon the disposition of a warm freezing tray in thermal contact with the evaporating unit.

Another object of the invention is to provide a refrigeration apparatus in which a section of an evaporating conduit embodied in a refrigerant evaporating unit, will be disposed in good thermal contact with a freezing tray, thus providing for the absorption of heat from the latter by an evaporating conduit section, at a relatively rapid rate.

Another object of the invention is to provide a refrigerant evaporating unit embodying an expansion conduit havin an end portion in thermal contact with a freezing tray, to which end portion, a thermostat for initiating the 0 eration of a refrigerant expan- 40 sion unit, is irectly attached.

Another object of the invention is to provide a refrigerant evaporating unit in which substances of various characters can be reduced very quickly to a frozen state, without materially affecting the normal temperature of such refrigeration apparatus in regions where substances are not required to be frozen.

Prior to the invention it has been the practice to employ refrigerant fluid evaporating L 1929. Serial N0. 854,847.

units of a size or capacity capable of maintaining the interior of a refrigerator cabinet at a predetermined moderately low temperature. In such refrigeration apparatus when it became desirable to freeze substances of any character, in trays employed for that purpose, they were merely placed in thermal contact with some portion of the evaporating unit and permitted to remain there often for several hours before the substances would become entirely frozen. By reason of the fact that such evaporating units were constructed primarily for the purpose of cooling a relatively large space to a predetermined low temperature, it was necessary, in order to decrease the freezing time, to change entirely the range of operation of the apparatus, as

a result of which a large amount of unnecessary work was done in cooling the entire refrigerator cabinet to a temperature lower than that which normally was required. Consequently, it was thought to be the better practice simply to provide a refrigerant evaporating unit of such size and capacity as to efficiently cool the larger portion of a refrigerator cabinet and to permit the freezing of substances therein at any rate at which an apparatus might be capable of performin this office.

i his invention comprehends the employment of a structure which is capable of operating etliciently in a refrigerator cabinet, both as a cooling unit under normal condition of operation; and, under special circumstances when it is particularly desirable to employ it as a freezin unit, to perform this function at a relatively rapid rate without materially affecting the temperature of a refrigerator cabinet in which the apparatus is employed.

The automatic operation of the structure embodying the invention is provided for by emplo ing a control apparatus of any suit- 1 able character for causing the operation of the expansion unit; and thus removing heat from a freezing tray whenever a tray containing a warm substance required to be frozen is inserted in the particular portion of the evaporating unit employed for this purpose. Such evaporating unit will operate capacity of the refrigerant condensing unit.

Since this section of the expansion conduit is capable of absorbing heat from a freezing tray having a much higher temperature, at a rate substantially equal to the capacit of the evaporatin unit, very little heat wi 1 beabsorbed by ot ier portions of the expansion ,conduit which are affected by substances having temperatures only slightly greater. than the latter.

For a better understanding of the invention, reference ma now be had to the accompanying drawing forming a part of this specification in which:

Figure 1 is a fragmentary cross-sectional view of a refrigerator cabinet comprising a refrigerant expansion unit embodying the invention;

Figure 2 is a longitudinal cross-sectional view of the refrigerant evaporating unit illustrated by Figure 1 Figure 3 is a fragmentary cross-sectional view of a freezing tray illustrating one form which the invention may assume;

Figure 4 is a dia ammatical view illustrating a form of re rigerant condensing unit which ma be incorporated in a structure embodying tlie invention.

A refrigerator cabinet 10, employed in practising the invention, is associated operatively with an electric motor 15 for driving a compressor 20, having a suction side communicating, through a suction line 11, with a refrigerant evaporating unit desig nated generally by the numeral 12.

The compressor also is connected to a condenser 25, into which the fluid withdrawn from the evaporating unit is discharged at an increased pressure, thus giving off its heat to the atmosphere or other suitable fluid at a lower t mperature employed for cooling purposes. From the condenser the refrigerant liquid is conducted, through a conduit 30, to a refrigerant expansion valve 13, from which it is expanded during the period of operation of the apparatus, into a helieally wound section 14 of a refrigerant expansion conduit 16. While the coil 14 has been illustrated asbeing of a helical formation, it is apparent that the conduit may be arranged in an other suitable manner.

n order to provide means upon which to support the refrigerant expansion valve 13, a brine tank 17 is provided with a boss 18 to which the aforesaid valve is adapted to be secured by bolts or other suitable means (not shown). Access to the interior of the tank 17 is provided by means of a filler cap 19 through zontally disposed sleeves, for example, such as that illustrated by the numeral 21, are

adapted to provide apertures projecting into the interior of the tank 17, into which freezing trays, of the character illustrated by the numeral 22, may be inserted. I

Grids, as illustrated by the numeral 23, may be employed in the ice trays 22, for the purpose of dividing the latter into a plurality of compartments for the reception of water or other substances desired to be frozen. In order to ensure a rapid rate of heat transfer between the tray 22 and the bottom of the sleeve 21, on which the former is supported, 1t is especially desirable to provide a large number of points of metallic contact between the two. Hence, if the bottom of a freezing tray is substantially of planular formation, then the portion of the sleeve in contact therewith should be of similar formation.

The end of the conduit 14 opposite the expansion valve 13 is provided with a bent portion 24, through which the latter communicates with a section 26, of the evaporating conduit 16. This conduit is wound longitudinally of the tank 17 in sinuous formation, and soldered, as indicated at 27, to the bottom of the sleeve 21, thus providing a very eflicient thermal contact between this section of the conduit and the ice tray 22.

If the brine tank 17 is provided with a plurality of sleeves 21, in which ice trays 22 are adapted to be inserted, or if a plurality of ice trays 22is supported in a single large sleeve 21, other sections of expansion coil similar to that designated by the numeral 26, may, or may not, be provided for each tray or sleeve, depending on whether it is prefera'gle to freeze the fluid in a single tray at a V ry rapid rate or to freeze the fluid in a plurality of trays at a lesser rate.

It is to be remembered that the capacity of any condensing unit is limited, and, consequently, it can not perform a large amount of work at as great a rate as a small amount of work, theoretically. can be performed by the same unit.

The end of the section 26 of the expansion conduit 16 emerges from the brine tank 17 through a eollar'29 soldered both to the tank and the conduit. An irregular bend 31 formed externally of the tank 17 merges into a horizontally disposed section 32 which extends across the end of the sleeve 21 in close proximity to the end of the tank.

A thermostat 33, which controls the operation of the evaporating unit, indirectly, by effecting the periodic energization of the motor 15- actuating the condensing unit, is connected by a metallic clip 34 to an end portion of the section 32 immediately adjacent the termination of the sleeve 21. The section 32 communicates directly with the suction line 11 connected to the suction side of the refrigerant compressor 20.

When the ice tray 22 is inserted in the sleeve 21, it is adapted at one end to contact 5 thermally with the section 32 of the evaporating conduit 16. In order to provide a more positive metallic contact between the end of the ice tray 22 and the section 32, a resilient coupling member 36, (see Fig. 3) soldered to the end of the tray 22, as indicated at 37, may beeinployed. Thus when the tray is thrust into the sleeve 21 the resilient member 36 is sprung open slightly in order to permit the entrance of the section 32 therein.

This structure obviously provides an excellent thermal contact between the tray and this portion of the evaporating conduit, and, consequently, the temperature of the latter will be increased almost immediately upon the insertion of the tray.

In the operation of the invention, when the tray 22, containing a warm substance of any character desired to be frozen, is inserted in the sleeve 21 and the end thereof contacts thermally with the section 32 of the evaporating conduit 16, the temperature of such section is increased rapidly by reason of the large temperature differential between them, and the heat absorbed by such section is conducted through the metallic clip 34 to the fluid containing bulb of the thermostat 33.

Since the path of heat conduction between the thermostat and the end of the tray 22 is relatively short, and there being substantially no means by which such heat units may be dissipated before reaching the bulb of the thermostat, an increase in temperature of the latter is effected within a. very short time. Thereupon, the thermostat automatically provides an electrical circuit in the motor 15 of the condensing unit, thus operating the latter and initiating a cycle of operation of the liquid refrigerant evaporating unit.

' Assuming that the apparatus had been operated normally just prior to the time when the freezing tray was inserted in the evaporating unit, it is obvious that the temperature of the brine in the tank 17 has been reduced to such an extent that the temperature differential between it and the evaporating conduit is relatively small. Thus, the only material temperature differential existing between any part of the expansion conduit and objects with which it is in thermal contact, is the temperature differential between section 26 of the coil and the freezing tray 22. In any event, this temperature differential is far in excess of any other affectin g the operation of the evaporating unit. In View of the fact that the section 26 of the evaporating conduit 16 is soldered to the bottom of the sleeve 21. and that the bottom of the freezing tray 22 is in good thermal contact with the sleeve 21, the heat units embodied in the substances in the freezing tra are absorbed by the section 26 at aver I rapid rate.

In an apparatus constructe according to this invention, this rate is "assumed to be great enough to cause the evaporation of substantially all of the Liquid discharged into the expansion coil through the expansion valve 13, or enough of such liquid to absorb substantlally all of the latent heat of fusion of the substances in the freezing tray 22, before the temperature of the end of the evaporating coil supporting the thermostat is reduced to such degree that the circuit through the motor will be broken.

If the substance in the'tray 22 is not entlrely frozen by a single cycle of operation of the apparatus, the temperature of the section 32 will be increased again in a very short time after the completion of the aforesaid cycle. The thermostat being affected by this increase in temperature of the section, it will quickl cause another cycle of operation to be initiated, as a consequence of which more heat will be extracted from the substance in the tray 22 before the thermostat is again compelled to discontinue the operation of the apparatus. In any event, the excellent thermal contact between the thermostat and the tray 22, will cause the operation of the refrigerating apparatus at very short intervals, until such time as the temperature differential between the substance in the tray 22, and the section 26 of the evaporating coil 16, is reduced to a relatively small minimum value.

It is to be understood that this invention is I not limited to an apparatus in which a brine tank is employed as a special heat retaining medium. Any other substances such as cast iron, aluminum, brass, earthenware or bituminous materials, may be employed instead of a brine tank if desired, or such heat retaining mediums may be dispensed with entirely. Likewise, the invention 1s not limited to any particular type of refrigeration apparatus or to the use of evaporating conduits as distinguished from other known structures for providing space in which evaporation of a fluid is adapted to occur.

While it is very desirable to provide an end section of theevaporating conduit in intimate thermal contact with an end portion of a freezing tray, a similar result may be obtained by providing any suitable form of medium in a region closely adjacent the heat conducting material upon which the freezing tray is supported. Itwill be noted that the drawing also embodiestlns form which the invention may assume.

Although the specification discloses only the preferred forms of this invention, and describes in detail only certain applications thereof, it will be apparent to those skilled in the art that the invention is not so limited, but that various modifications and changes may bemade therein without departing from the spirit of the invention or from the scope of the appended claims.

I claim:

l. A refrigerant evaporating unit comprising a heat retaining medium having an aperture formed therein, a refrigerant evaporating conduit associated with the heat retain ing medium, said conduit having an end portion in thermal contact with a freezing tray, and a thermostat in thermal contact with said end portion for initiating the operation of the evaporating unit.

2. A refrigerant evaporating unit comprising a refrigerant expansion conduit having an end portion in thermal contact with a freezing tray adapted to be associated therewith, and a thermostat in thermal contact with said end portion for initiating the operation of the refrigerant evaporating unit.

3. A refrigerant evaporating unit comprising a refrigerant evaporating conduit having an end portion, and a freezing tray having a resilient member normally contacting said end portion.

4. A refrigerant evaporating unit comprising a refrigerant evaporating conduit having an end portion, a freezing tray having a resilient member for thermally contacting said end portion, and a thermostat associated in heat conducting relation to the aforesaid end portion for initiat ng the operation of the refrigerant evaporating unit.

5. A refrigerant evaporating unit comprising a refrigerant evaporating conduit having an end portion, a freezing tray disposed in thermal contact with said end portion, and a metallic member for connecting a thermostat directly to the aforesaid end portion.

6. A refrigerant evaporating unit surrounded by a circulating medium comprising an evaporating coil having a helically wound section and a sinuously wound section, said last mentioned section being disposed in a horizontal plane, a freezing tray supported by said last mentioned section in thermal contact therewith, and a thermostat responsive to the temperature of the freezing tray for initiating the operation of the refrigerant evaporating unit, and being disposed in the path of the circulatin medium surrounding such unit for discontlnuing its operation.

7. A refrigerant evaporating unit comprising a brine tank having a horizontally disposed aperture formed therein, a freezing tray adapted to be supported in such aperture, a refrigerant evaporating conduit associated with the brine tank and having an end portion disposed in thermal contact with the end portion of the aforesaid freezin tray, and a thermostat connected to the en portion of the evaporating conduit in close proximity to the aforesaid end portion of the freezing tray.

8. A refrigerant expansion unit comprising a heat retaining medium having an expansion conduit associated therewith in thermal contact with a freezing tray, and a thermostat conjunctively connected to the freezing tray and the evaporation conduit through a thermally conductive path of low resistance.

9. A refrigerant evaporating unit surrounded by a circulating medium comprising a helically wound section of an evaporating coil adapted to absorb heat from a brine tank, a second section of evaporating conduit communicating with the first and arranged tangentially relative to a horizontal plane, a freezing tray having a bottom portion in thermal contact with the last mentioned section of the evaporating conduit, and a thermostatic element having direct metallic engagement with the freezing tray and being arranged in the path of the circulating medium surrounding the unit.

10. A refrigerant evaporator comprising a brine tank having a horizontally disposed sleeve formed therein, a freezing tray adapted to be supported within the sleeve, an evaporating conduit having a section located above said sleeve, a section disposed in thermal contact with a portion of the tank forming the bottom of the sleeve, and a. thermostat conjunctively connected to the freezing tray and the evaporating conduit through a signature.

GEORGE W. MASON. 

